1. Field of the Invention
The present invention relates to a portable electronic apparatus, an operation control method adopted by the portable electronic apparatus and an operation control program implementing the operation control method. More particularly, the present invention relates to a portable electronic apparatus having an acceleration detection unit configured to detect an acceleration, an operation control method usable in the portable electronic apparatus and an operation control program implementing the operation control method. In addition, the present invention also relates to an evaluation-signal generation apparatus for generating an evaluation signal on the basis of an acceleration detected by the acceleration detection unit as a signal optimum for detection of a predetermined movement of the portable electronic apparatus and relates to a signal generation method adopted by the evaluation-signal generation apparatus.
2. Description of the Related Art
The reader is suggested to refer to Japanese Patent Laid-open No. 2006-17874 used as Patent Document 1 and Japanese Patent Laid-open No. Hei 2-69693 used as Patent Document 2.
In some cases, the number of operation components that can be employed in an electronic apparatus or, in particular, a portable electronic apparatus, is deliberately limited due to reasons such as a small-size requirement for improving the portability of the apparatus and a design requirement of the apparatus. For example, some portable music players or the like employ only basic-operation components such as playback, stop and volume-adjustment buttons. In the case of such a portable electronic apparatus, the user carries out operations other than the basic operations by typically making use of a menu appearing on a display screen of the apparatus. In this way, the portable electronic apparatus allows the user to carry out operations other than the basic operations while having a compact size and an improved design. If the user has to carry out a specific operation other than the basic operations on the portable electronic apparatus by making use of a menu appearing on a display screen of the apparatus, however, the user may have to go through a number of hierarchical menu layers till the user reaches a desired menu item representing the specific operation. Thus, the designer of the portable electronic apparatus has to consider fear of the deteriorated operatability of the apparatus.
On the other hand, some portable electronic apparatus designed in recent years employ an interface for detecting an operation carried out by the user by making use of an acceleration sensor. For example, Patent Document 1 describes a portable electronic apparatus capable of detecting a movement caused by the user as a movement of the apparatus on the basis of a signal generated by an acceleration sensor employed in the apparatus and issuing a predetermined instruction on the basis of a result of the detection (an example of the movement caused by the user is a movement caused by hand shaking or hand striking). On the other hand, Patent Document 2 describes a portable electronic apparatus capable of detecting a movement caused by the user as a movement of the apparatus on the basis of a signal generated by an acceleration sensor employed in the apparatus in the same way as the apparatus disclosed in Patent Document 1 and changing the mode of a clock on the basis of a result of the detection. Since the portable electronic apparatus is capable of detecting a movement caused by the user as a movement of the apparatus on the basis of a signal generated by an acceleration sensor employed in the apparatus as described above, the number of operation components to be provided in the apparatus can be reduced by a quantity according to the capability.